It’s interesting because I’ve seen the idea of Korra dying young many times. I’m sure it comes from the fact that Aang did due to the time in the iceberg and people assume the poison would have the same effect.
But I actually head canon that Korra outlives Kyoshi as the longest-lived Avatar ever.
I see that as a possibility, but not an eventuality. Korra’s still young enough that her gradual recovery from the poison incident (after Toph’s help) should lead to her being stronger and more resilient afterwards. There are plenty of young WWII vets and Holocaust survivors who survived serious injuries and long-term conditions and went on to enjoy very, very long, full lives.
But In my headcannon, Korra and Asami (in their early 100s) attend the funeral of Opal, their last living contemporary friend. (Mako dies young, say in his mid-to-late 40s,a victim of his career. Bolin lives well into his 80s before suffering a heart attack.) Then Korra and Asami reveal their plan for their future to what’s left of their ‘family’: since during Korra’s tenure as the Avatar the Avatar’s connection to the spirits of the past Avatars was permanently severed, and Korra remains the last living avatar to have had such contact, Korra and Asami will enter the Spirit World together and surrender their mortal bodies, to become the teachers and guides for future generations of Avatars.
They bid tearful farewells to Kai, Ikki, Rohan, Meelo and their ‘adopted’ ‘nieces’ and ‘nephews’ (Bolin and Opal’s kids, Kai and Jinora’s kids, etc.) in a sort of ‘living funeral’. Then Jinora leads them both in meditation over to the Spirit world, where they first spent time together as a couple and as lovers and where they choose to remain, in the same forms and apparent-ages at which they first entered the Spirit world together. They dwell there together perpetually, sometimes in the company of Iroh, a dear old friend, but more often alone together – ‘happily ever after’ – as the show-runners put it, wandering the woods and beaches of the Spirit world, but with a permanent residence in the general vicinity of the Spirit World’s Republic City portal, waiting for the arrival of the next Avatar. Jinora visits them often, and late in her own life – after Kai’s passing – she chooses to join them there.
SittingOverHereDreaming 